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Papirex

May 6, 2006, 11:43 AM

Re: [Rolly] Back up power supply. Did I waste my pesos?

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Rolly is right about the horrors of the wiring in some homes in Mexico. If all the circuits in a house are protected by breakers, the fuses at the main disconnect switch for the house are superfluous and unneeded. They are sometimes even a problem. The “electricians” here also have a bad habit of fusing the neutral wire. That should never be done.

Fuses for the main electrical service are never used in The US, just a main disconnect switch at the service entrance. The breakers on every circuit protect the house wiring.

The fuses used in Mexico have a replaceable element inside them. If a fuse blows, you can simply replace the fuse element, instead of the whole fuse. The problem is that sometimes the end of the element, where it contacts the metal end of the fuse will become burned, just like the electrical contacts in any switch will sometimes do.

We lived in one house where the voltage was constantly fluctuating. Sometimes the TV would just drop out, and the UPS for my computer was intermittently coming on and off. I checked the voltage many times, and it was constantly fluctuating between 80 and 130 volts within a few minutes.

I called the electric company, they sent a man out to our house and he said the problem was not theirs, he recommended that I hire an electrician to check the house wiring. I am a retired process control instrument technician and I know electricity pretty well.

I figured, hell, if the problem is in the house wiring, I can fix it myself. After a few weeks of trying to analyze the problem and finding no faults in the house I finally gave up. I hired an electrician. After checking everything in the house that I had already checked, he checked the Main entrance fuses.

When he told me that the problem was with the fuses, I thought he was crazy and I had made a mistake hiring him. Where I come from a fuse is either good, or it is blown. Not here. When he realized I didn’t believe him, he unscrewed one of the metal end caps on the fuses. Sure enough the interior replaceable elements were burned where they contacted the metal end caps of the fuse. That’s when I learned how fuses are made in Mexico.

He didn’t have the right sized replacement elements with him, so he cleaned the ends of the elements a little bit with a knife blade. That helped, but it didn’t cure the problem. The voltage fluctuation did not go as low as before he did that. I had to buy new elements the next day. I thought the problem was cured. It wasn’t.

I still had some voltage fluctuations. Not as severe as before, but noticeable. I called the electrician back. He discovered a second set of main fuses inline with the first set in a box on the wall beside our driveway. The second set of fuses was repetitious and totally unnecessary.

Rather than jumpering those fuses and taking them out of the circuit, I took the easy way out and replaced the elements in them too. We knew we were moving.

There are many wiring surprises in Mexico. Unless you or a friend have enough knowledge to know that an electrician is qualified, do not believe a thing they tell you. When I asked one of them about grounding some outlets, he told me, “Oh, we don’t do that in Mexico, it isn’t necessary.” When I asked him about the wall outlets with a built in breaker with a reset button on them, that will trip if a short circuit is detected, He said “We don’t use them here either, they don’t work.” Of course they won’t work if there is no ground wire.

For anyone thinking of moving here and buying a house, there are some pretty good books dealing with do-it-yourself wiring and plumbing available. One place to buy them is at Home Depot. I recommend buying copies of both. They sell those books at Home Depot here in Cuernavaca, but I have never looked at them here to see if they are in English or Spanish.

Rex

"The supreme happiness of life is the conviction that we are loved" - Victor Hugo

(This post was edited by RexC on May 6, 2006, 11:47 AM)

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